System and method for adjusting a control loop bandwidth

ABSTRACT

The present invention provides a control loop bandwidth adjusting system for adjusting a control loop bandwidth of an optical reproducing device. The optical reproducing device comprises a data signal processing circuit, which uses the control loop bandwidth to process the data signal. The control loop bandwidth adjusting system comprises a control loop bandwidth generator for generating the control loop bandwidth and a control loop bandwidth adjusting module for adjusting the control loop bandwidth according to whether a defect signal corresponding to the defective data is received or not. If the control loop bandwidth adjusting module receives the defective data entry signal, the defective data duration signal, and the defective data exit signal, the control loop bandwidth is adjusted to a first bandwidth value, a second bandwidth value, and a third bandwidth value respectively.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a control loop bandwidthadjusting method for adjusting a control loop bandwidth of an opticalreproducing device, and more particularly to a data signal processingcircuit for processing the data signal with the control loop bandwidth.

[0003] 2. Description of the Prior Art

[0004] Please refer to FIG. 1. FIG. 1 is a schematic diagram that anoptical reproducing device 10 reads a data signal from an opticalrecording medium 12 according to the prior art. When the opticalreproducing device 10 reads the data signal from the optical recordingmedium 12, an optical pickup head 14 uses a laser beam 16 to focus onthe optical recording medium 12 in a predetermined distance and to writeor read the corresponding optical data into or from the opticalrecording medium 12.

[0005] Generally, for writing or reproducing the optical datacompletely, a data signal processing circuit 18 is used for assisting inprocessing the data signal. The data signal processing circuit 18 can bea servo control circuit, a data/clock recovery PLL, or a slicer. Thedata signal processing circuit 18 can be a servo control circuit forprocessing actuation control to the optical pickup head 14, a data/clockrecovery PLL for synchronizing the data signal, or a slicer for slicingthe data signal.

[0006] However, when the optical reproducing device 10 reads thedefective data signal from the optical recording medium 12, thedefective data signal will generate a corresponding defective datasignal, and the defective data signal will cause the optical reproducingdevice 10 to read incorrect data signals, then the data signalprocessing circuit 18 will perform an incorrect process.

SUMMARY OF THE INVENTION

[0007] It is therefore a primary objective of the present invention toprovide a control loop bandwidth adjusting method for adjusting acontrol loop bandwidth of an optical reproducing device. The data signalprocessing circuit processes the data signal by means of the controlloop bandwidth.

[0008] The present invention provides a control loop bandwidth adjustingsystem for adjusting a control loop bandwidth of an optical reproducingdevice. The optical reproducing device comprises a data signalreproducing circuit, a data signal processing circuit, and a defectdetection circuit. The data signal reproducing circuit is used forreproducing a data signal from an optical recording medium. The datasignal processing circuit processes the data signal by means of thecontrol loop bandwidth. The defect detection circuit is used fordetecting if there is any defective data signal on the optical recordingmedium, and generating a set of corresponding defective data signalsduring the occurrence of the defective data signal. The control loopbandwidth adjusting system comprises a control loop bandwidth generatorand a control loop bandwidth adjusting module. The control loopbandwidth generator is used for generating the control loop bandwidth,and the control loop bandwidth is adjusted to one of the followingvalues, a predetermined bandwidth value, a first bandwidth value, asecond bandwidth value, and a third bandwidth value. The control loopbandwidth adjusting module is used for receiving the set of defectivedata signals to adjust the bandwidth value of the control loopbandwidth. If the control loop bandwidth adjusting module receives theset of defective data entry signals, adjust the control loop bandwidthto the first bandwidth value and make the data signal processing circuitprocess the data signal with the first bandwidth value. If the controlloop bandwidth adjusting module receives the set of defective dataduration signals, adjust the control loop bandwidth to the secondbandwidth value and make the data signal processing circuit process thedata signal with the second bandwidth value. If the control loopbandwidth adjusting module receives the set of defective data exitsignals, the control loop bandwidth is adjusted to the third bandwidthvalue and make the data signal processing circuit process the datasignal with the third bandwidth value. If the control loop bandwidthadjusting module does not receive the defective data signals anymore,the control loop bandwidth value is recovered to the predeterminedbandwidth value and make the data signal processing circuit process thedata signal with the recovered control loop bandwidth.

[0009] By dynamically adjusting the different control loop bandwidthvalues in the different phases after data defect, the opticalreproducing device will not make the data signal processing circuitperform an incorrect process as reproducing the defective data signal.The optical reproducing device can speed up the data signal processingcircuit to use the signals of the normal area when the defect enters orexits.

[0010] These and other objects, features and advantages of the presentinvention will become apparent from the following detailed descriptionof illustrative embodiments thereof, which is to be read in connectionwith the accompanying drawings.

BRIEF DESCRIPTION OF THE APPENDED DRAWINGS

[0011]FIG. 1 is a schematic diagram that an optical reproducing devicereads a data signal from an optical recording medium according to theprior art;

[0012]FIG. 2 is a block diagram of a control loop bandwidth adjustingsystem and an optical reproducing device according to the presentinvention;

[0013]FIG. 3A is a schematic diagram of a defective data signalaccording to the present invention;

[0014]FIG. 3B is a schematic diagram of another defective data signalaccording to the present invention; and

[0015]FIG. 4 is a flowchart of a control loop bandwidth adjusting methodaccording to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0016] Please refer to FIG. 2. FIG. 2 is a block diagram of a controlloop bandwidth adjusting system 30 and an optical reproducing device 32according to the present invention. The control loop bandwidth adjustingsystem 30 of the present invention is used for adjusting a control loopbandwidth of an optical reproducing device 32. The optical reproducingdevice 32 comprises a data signal reproducing circuit 34, a data signalprocessing circuit 36, and a defect detection circuit 38. The datasignal reproducing circuit 34 is used for reproducing a data signal froman optical recording medium, and the data signal may be a RF signal. Thedata signal processing circuit 36 processes the data signal by means ofthe control loop bandwidth. The defect detection circuit 38 is used fordetecting if there is any defective data signal on the optical recordingmedium, and generating a set of corresponding defective data signalsduring the occurrence of the defective data. The defect detectioncircuit 38 not only detects if there is any defective data signal on theoptical recording medium but also detects if there is a defective dataentry signal, a defective data duration signal, or a defective data exitsignal.

[0017] The control loop bandwidth adjusting system 30 of the presentinvention comprises a control loop bandwidth generator 40 and a controlloop bandwidth adjusting module 42. The control loop bandwidth generator40 is used for generating the control loop bandwidth, and the controlloop bandwidth can be adjusted to a predetermined bandwidth value, afirst bandwidth value, a second bandwidth value, and a third bandwidthvalue. The control loop bandwidth adjusting module 42 is used forreceiving the set of defective data signals to adjust the bandwidthvalues of the set of the control loop bandwidths.

[0018] If the control loop bandwidth adjusting module 42 receives theset of defective data entry signals, which means that the control loopbandwidth adjusting system 30 receives the set of defective data entrysignals, the control loop bandwidth is adjusted to the first bandwidthvalue and the data signal processing circuit 36 processes the datasignal with the first bandwidth value. If the control loop bandwidthadjusting module 42 receives the set of defective data duration signals,the control loop bandwidth is adjusted to the second bandwidth value andthe data signal processing circuit 36 processes the data signal with thesecond bandwidth value. If the control loop bandwidth adjusting module42 receives the set of defective data exit signals, the control loopbandwidth is adjusted to the third bandwidth value and the data signalprocessing circuit 36 processes the data signal with the third bandwidthvalue. If the control loop bandwidth adjusting module 42 does notreceive the defective data signals anymore, which means that the controlloop bandwidth adjusting system 30 does not receive the defective datasignals anymore, the control loop bandwidth value is recovered to thepredetermined bandwidth value and the data signal processing circuit 36processes the data signal with the recovered control loop bandwidth.

[0019] As shown in FIG. 2, in the control loop bandwidth adjustingsystem 30, the data signal processing circuit 36 has a lot of functions.The data signal processing circuit 36 may be a servo control circuit forcontrolling an optical pickup head of the optical reproducing device 32to read the data signal from the optical recording medium. The servocontrol circuit will speed up, slow down, or stop the actuation controlto the optical pickup head as receiving the adjusted control loopbandwidth and resume the original actuation control to the opticalpickup head as receiving the recovered control loop bandwidth.

[0020] The data signal processing circuit 36 may be a data/clockrecovery PLL. The data/clock recovery PLL will speed up, slow down, orstop to synchronize the data signal as receiving the adjusted controlloop bandwidth and resume the original synchronization to the datasignal as receiving the recovered control loop bandwidth. The datasignal processing circuit 36 may also be a slicer. The slicer will speedup, slow down, or stop the slicing level control of the data signal asreceiving the adjusted control loop bandwidth and resume the originalslicing level control of the data signal as receiving the recoveredcontrol loop bandwidth.

[0021] Please refer to FIG. 3A. FIG. 3A is a schematic diagram of adefective data signal according to the present invention. In the controlloop bandwidth adjusting system 30 of the preferred embodiment in FIG.2, the set of defective data signals generated by the defect detectioncircuit 38 are determined by a set of signals. The set of signalscomprise a defect entry signal 46, a defect duration signal 44, and adefect exit signal 50. The defect detection circuit 38 comprises apredetermined first defect level and a predetermined second defectlevel. The defect detection circuit 38 generates a first defect signal52 when the data signal is lower than the first defect level. The firstdefect signal 52 starts at time T2 and ends at time T8. The defectdetection circuit 38 generates a second defect signal 54 when the datasignal is lower than the second defect level. The second defect signal54 starts at time T4 and ends at time T6. According to the relationshipbetween the first defect signal 52 and the second defect signal 54, thedefect entry signal 46, the defect duration signal 44, the defect exitsignal 50 can be obtained, and the defective data signal can be furtherobtained.

[0022] Besides, please refer to FIG. 3B. FIG. 3B is a schematic diagramof another defective data signal according to the present invention.According to the relationship between the first defect signal 56 and thesecond defect signal 58 generated by a predetermined delay value 60 andvalue 61, the present invention can generate the defect entry signal 46,the defect duration signal 44, and the defect exit signal 50. The firstdefect signal 56 starts at time T2 and ends at time T6, and the seconddefect signal 58 starts at time T4 and ends at time T8.

[0023] Please refer to FIG. 4. FIG. 4 is a flowchart of a control loopbandwidth adjusting method according to the present invention. Thepresent invention provides a control loop bandwidth adjusting method foradjusting a control loop bandwidth of an optical reproducing device 32.The optical reproducing device 32 comprises a data signal processingcircuit 18, which processes a data signal by means of the control loopbandwidth. The adjusting method of the present invention is described inthe following by FIG. 2 and FIG. 4.

[0024] First, in step S02, the data signal is read from an opticalrecording medium by the optical reproducing device 32. The data signalcan be a RF signal. In step S04, according to a predetermined bandwidthvalue of the control loop bandwidth, the data signal is processed by thedata signal processing circuit 18. In step S06, if the control loopbandwidth adjusting system receives the defective data entry signal asreproducing the data signal, which represents the defective data entrysignal is detected by the optical reproducing device 32, the controlloop bandwidth value is adjusted. In step S08, the data signalprocessing circuit 18 processes the data signal with the adjustedcontrol loop bandwidth. In step S10, if the control loop bandwidthadjusting system receives the defective data duration signal asreproducing the data signal, which represents that the defective dataduration signal is detected by the optical reproducing device 32, thecontrol loop bandwidth value is adjusted. In step S12, the data signalprocessing circuit 18 processes the data signal with the adjustedcontrol loop bandwidth. In step S14, if the control loop bandwidthadjusting system receives the defective data exit signal as reproducingthe data signal, which represents that the defective data exit signal isdetected by the optical reproducing device 32, the control loopbandwidth value is adjusted. In step S16, the data signal processingcircuit 18 processes the data signal with the adjusted control loopbandwidth. In step S18, if the control loop bandwidth adjusting system30 doesn't receive the defective data signal anymore as reproducing datasignal, which represents the defective data signal is not detected bythe optical reproducing device 32 anymore, the control loop bandwidthvalue is recovered to the predetermined bandwidth value. Finally, instep S20, the data signal processing circuit 18 processes the datasignal with the recovered control loop bandwidth.

[0025] According to the adjusting method of the above, the data signalprocessing circuit 36 can be a servo control circuit, a data/clockrecovery PLL, or a slicer as the same in the above-mentioned adjustingsystem 30.

[0026] The adjusting method shown in FIG. 4, the optical reproducingdevice 32 further comprises a defect detection circuit 38, and thefunctions thereof and the method of generating the defect entry signal,the defect duration signal, and the defect exit signal are shown in FIG.3A and FIG. 3B.

[0027] Therefore, the present invention provides a control loopbandwidth adjusting system 30 for adjusting a control loop bandwidth ofan optical reproducing device 32. If the control loop bandwidthadjusting module receives the set of defective data entry signals 46,the control loop bandwidth is adjusted to the first bandwidth value andthe data signal processing circuit 36 processes the data signal with thefirst bandwidth value. If the control loop bandwidth adjusting modulereceives the set of defective data duration signals 44, the control loopbandwidth is adjusted to the second bandwidth value and the data signalprocessing circuit 36 processes the data signal with the secondbandwidth value. If the control loop bandwidth adjusting module receivesthe set of defective data exit signals 50, the control loop bandwidth isadjusted to the third bandwidth value and the data signal processingcircuit 36 processes the data signal with the third bandwidth value.According to the above, due to using the specific and adjusted bandwidthvalue respectively at different times in the defective data area, theoptical reproducing device 32 will not make the data signal processingcircuit 36 perform an incorrect process by reproducing the defectivedata signal. The optical reproducing device 32 adopts another properbandwidth value to use the useful data signal between the normal anddefect area.

[0028] While the invention has been described in the preferredembodiments, it is understood that the used words are words ofdescription rather than words of limitation and that changes within thepurview of the appended claims may be made without departing from thescope and spirit of the invention in its broader aspect.

What is claimed is:
 1. A control loop bandwidth adjusting method foradjusting a control loop bandwidth of an optical reproducing device, theoptical reproducing device comprising a data signal processing circuitwhich processes a data signal by means of the control loop bandwidth,the adjusting method comprising the steps of: reproducing the datasignal from an optical recording medium by the optical reproducingdevice; according to a predetermined bandwidth value of the control loopbandwidth, processing the data signal by the data signal processingcircuit; if a defective data entry signal is detected by the opticalreproducing device as reproducing the data signal, adjusting the controlloop bandwidth to a first bandwidth value and making the data signalprocessing circuit process the data signal with the adjusted controlloop bandwidth; if a defective data duration signal is detected by theoptical reproducing device as reproducing the data signal, adjusting thecontrol loop bandwidth to a second bandwidth value and making the datasignal processing circuit process the data signal with the adjustedcontrol loop bandwidth; if a defective data exit signal is detected bythe optical reproducing device as reproducing the data signal, adjustingthe control loop bandwidth to a third bandwidth value and making thedata signal processing circuit process the data signal with the adjustedcontrol loop bandwidth; and if a defective data signal is not detectedby the optical reproducing device anymore as reproducing the datasignal, recovering the control loop bandwidth value to the predeterminedbandwidth value and making the data signal processing circuit processthe data signal with the recovered control loop bandwidth.
 2. Theadjusting method of claim 1, wherein the data signal processing circuitis a servo control circuit for controlling an optical pickup head of theoptical reproducing device to read the data signal from the opticalrecording medium, and the servo control circuit will speed up, slowdown, or stop the actuation control to the optical pickup head asreceiving the adjusted control loop bandwidth, while the servo controlcircuit will resume the original actuation control to the optical pickuphead as receiving the recovered control loop bandwidth.
 3. The adjustingmethod of claim 1, wherein the data signal processing circuit is adata/clock recovery PLL, and the data/clock recovery PLL will speed up,slow down, or stop to synchronize the data signal as receiving theadjusted control loop bandwidth, while the data/clock recovery PLL willresume the original synchronization to the data signal as receiving therecovered control loop bandwidth.
 4. The adjusting method of claim 1,wherein the data signal processing circuit is a slicer, and the slicerwill speed up, slow down, or stop the slicing level control of the datasignal as receiving the adjusted control loop bandwidth, while theslicer will resume the original the slicing level control of the datasignal as receiving the recovered control loop bandwidth.
 5. Theadjusting method of claim 1, wherein the data signal is a data RFsignal.
 6. The adjusting method of claim 1, wherein the opticalreproducing device further comprises a defect detection circuit fordetecting if there are a defective data entry signal, a defective dataduration signal, and a defective data exit signal, and if the occurrenceof the defective data is terminated.
 7. The adjusting method of claim 6,wherein the defect detection circuit will generate a set ofcorresponding defective data signals during the occurrence of thedefective data.
 8. The adjusting method of claim 7, wherein the set ofdefective data signals are determined by a set of signals, and the setof signals comprise a defect entry signal, a defect duration signal, anda defect exit signal.
 9. The adjusting method of claim 8, wherein thedefect detection circuit comprises a predetermined first defect leveland a predetermined second defect level, generating a first defectsignal when the data signal is lower than the first defect level and asecond defect signal when the data signal is lower than the seconddefect level, according to the relationship between the first defectsignal and the second defect signal, getting the defect entry signal,the defect duration signal, and the defect exit signal.
 10. Theadjusting method of claim 8, wherein the defect detection circuitcomprises a predetermined defect level and two predetermined delayvalues, generating a first defect signal when the data signal is lowerthan the defect level and getting a second defect signal by delaying thepredetermined delay values according to the edge of the first defectsignal, according to the relationship between the first defect signaland the second defect signal, getting the defect entry signal, thedefect duration signal, and the defect exit signal.
 11. A control loopbandwidth adjusting system for adjusting a control loop bandwidth of anoptical reproducing device, the optical reproducing device comprising: adata signal reproducing circuit for reproducing a data signal from anoptical recording medium; a data signal processing circuit for using thecontrol loop bandwidth to process the data signal; a defect detectioncircuit for detecting if there is any defective data signal on theoptical recording medium, and generating a set of correspondingdefective data signals during the occurrence of the defective data. thecontrol loop bandwidth adjusting system comprising: a control loopbandwidth generator for generating the control loop bandwidth, thecontrol loop bandwidth being adjusted to one of the following values, apredetermined bandwidth value, a first bandwidth value, a secondbandwidth value, and a third bandwidth value; and a control loopbandwidth adjusting module for receiving the set of defective datasignals to adjust the bandwidth value of the control loop bandwidth;wherein if the control loop bandwidth adjusting module receives the setof defective data entry signals, adjusting the control loop bandwidth tothe first bandwidth value and making the data signal processing circuitprocess the data signal with the first bandwidth value, if the controlloop bandwidth adjusting module receives the set of defective dataduration signals, adjusting the control loop bandwidth to the secondbandwidth value and making the data signal processing circuit processthe data signal with the second bandwidth value, if the control loopbandwidth adjusting module receives the set of defective data exitsignals, adjusting the control loop bandwidth to the third bandwidthvalue and making the data signal processing circuit process the datasignal with the third bandwidth value, and if the control loop bandwidthadjusting module does not receive the defective data signals anymore,recovering the control loop bandwidth value to the predeterminedbandwidth value and making the data signal processing circuit processthe data signal with the recovered control loop bandwidth.
 12. Theadjusting method of claim 11, wherein the data signal processing circuitis a servo control circuit for controlling an optical pickup head of theoptical reproducing device to read the data signal from the opticalrecording medium, and the servo control circuit will speed up, slowdown, or stop the actuation control to the optical pickup head asreceiving the adjusted control loop bandwidth, while the servo controlcircuit will resume the original actuation control to the optical pickuphead as receiving the recovered control loop bandwidth.
 13. Theadjusting method of claim 11, wherein the data signal processing circuitis a data/clock recovery PLL, and the data/clock recovery PLL will speedup, slow down, or stop to synchronize the data signal as receiving theadjusted control loop bandwidth, while the data/clock recovery PLL willresume the original synchronization to the data signal as receiving therecovered control loop bandwidth.
 14. The adjusting method of claim 11,wherein the data signal processing circuit is a slicer, and the slicerwill speed up, slow down, or stop the slicing level control of the datasignal as receiving the adjusted control loop bandwidth, while theslicer will resume the original slicing level control of the data signalas receiving the recovered control loop bandwidth..
 15. The adjustingsystem of claim 11, wherein the data signal is a data RF signal.
 16. Theadjusting system of claim 11, wherein the defect detection circuitdetects the data signal of the optical recording medium if there are adefective data entry signal, a defective data duration signal, and adefective data exit signal, and if the occurrence of the defective datais terminated.
 17. The adjusting system of claim 16, wherein the set ofdefective data signals comprise a defect entry signal, a defect durationsignal, and a defect exit signal.
 18. The adjusting system of claim 17,wherein the defect detection circuit comprises a predetermined firstdefect level and a predetermined second defect level, generating a firstdefect signal when the data signal is lower than the first defect leveland a second defect signal when the data signal is lower than the seconddefect level, according to the relationship between the first defectsignal and the second defect signal, getting the defect entry signal,the defect duration signal, and the defect exit signal.
 19. Theadjusting system of claim 18, wherein the defect detection circuitcomprises a predetermined defect level and two predetermined delayvalues, generating a first defect signal when the data signal is lowerthan the defect level and getting a second defect signal by delaying thepredetermined delay values according to the edge of the first defectsignal, according to the relationship between the first defect signaland the second defect signal, getting the defect entry signal, thedefect duration signal, and the defect exit signal.